Question 225080 in Flutter Question posted in
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Flutter – How can I save the data of a document but changing one of the values

Using this I use the id of the document to identify the document that I want to modify but what if want to use a value inside of that document instead? For example:

dbUserDoc.collection('shoplist').get().then((querySnapshot) => {
            // ignore: avoid_function_literals_in_foreach_calls
            querySnapshot.docs.forEach((result) {
              final docPro = FirebaseFirestore.instance
                  .collection('products')
                  .doc(result.id); //here i use the document id but i want to use a value inside of that document
              print(result.id);
              docPro.get().then((DocumentSnapshot doc) {
                final data = doc.data() as Map<String, dynamic>;
                final int stockInt =
                    data['stock'] - int.parse(result['quantity']);
                final stock = <String, int>{"stock": stockInt};
                docPro.set(stock, SetOptions(merge: true));
              });
            })
          });

example

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2

Answers


  1. 0

    The result object is an object of type DocumentSnapshot. If you want to display the value of a field, not the value of the document ID, which in your case are the same, then please use:

    print(result[id]);

    This means that you’ll print the value of the id field that exists inside the document.

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  2. 0

    If you want to show the value of the id field inside of the products document, you can do:

    final product = result.data() as Map<String, dynamic>;
print(product["id"]);
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